Prosthetic liner with perspiration elimination mechanism

ABSTRACT

A prosthetic elastomeric liner, which can be used without lanyards or straps, in which, upon ambulation, perspiration is voided simultaneously with the reestablishment of a vacuum-aided seal without a vacuum pump. The liner&#39;s distal tip comprises a buttress anchored sweat port containing a one way valve continuous with a channel passing through the buttress and liner from its inner surface to its outer surface. The sweat port is connected, optionally integrally, to a prosthetic pin which is inserted into a prosthetic limb.

PRIORITY

This application is a continuation-in-part of U.S. Non-provisionalapplication Ser. No. 12/482,364 filed on Jun. 10, 2009, which claimspriority to U.S. Provisional Application No. 61/207,876, filed on Jun.10, 2008, which is hereby incorporated by reference.

BACKGROUND

A challenging aspect of treating those who have lost one or more limbsis the restoration of function to the remaining limb (residual limb).Such a restoration often means fitting the residual limb with one ormore prostheses, or artificial limbs. A difficulty with artificial limbsis that they often do not physically interface well with the prostheticpatient. For instance, most prostheses comprise a cup, or “socket” intowhich the residual limb, protected by a sheath or “liner,” is insertedand secured. Over the years, the wearing of prosthetics has become morecomfortable due to the adoption of prosthetic liners made of syntheticelastomeric and gel materials. Elastomeric liners have the ability tointerface between the skin of the wearer and the hard plastic orthoticsocket because they have elastic properties and physical consistenciessimilar to human tissue and can form a vacuum-aided seal between linerand residual limb. As a result, slipping and buckling with ambulation, aproblem with earlier liner types, can be reduced. Such liners areindicated in U.S. Pat. Nos. 5,549,709; 6,645,253; 6,761,742; 6,554,868;6,726,726; 6,926,742 and 6,974,484.

Current gel liner designs available to amputees are generally simple.Many are based upon a single-layer elastomeric sleeve, usually with aslight taper from the open end to a blunted closed end. Because of suchsimplicity of design, the liners can be manufactured in large numbersfrom easily worked materials at a relatively low cost.

A problem with elastomerics is their ability to thermally insulate,which tends to increase the rate at which the residual limb perspires.The supple elasticity which makes elastomeric liners suitable for longterm skin contact can have negative consequences when the contact withthe skin is broken by a liquid, such as perspiration. While mildperspiration may enhance the seal between the residual limb and theliner, the amount produced quickly increases such that a layer ofperspiration is formed between the liner surface and the residual limbsurface.

Because of the pressures exerted on the liner during ambulation,particularly by the prosthetic socket, the liner can pull away from theresidual limb, causing air to be sucked into the liner. As the airpockets join upon further ambulation, a volume is produced between theliner and the limb. The air in the volume contracts and expands witheach step, creating a suction and causing the residual limb to expandinside the liner. Such an expansion affects the fit of the limb andliner inside the socket. Many methods for fitting the limb inside theprosthetic socket can require that the limb be repositioned in order togive a comfortable fit. However, upon cessation of ambulation, such aswhile sitting down or sleeping, it is not uncommon for the residual limbto shrink inside the liner to its original size, necessitating yetanother refitting. Thus, it is of paramount importance that air beexcluded from the liner. Toward that end, it is thus important that thebuild-up of perspiration be prevented, and that perspiration be removedas it is being formed, or soon thereafter, from between the liner andthe residual limb.

Methods of attaching the liner-covered residual limb into the orthoticsocket figure significantly in the sliding caused by perspiration. Forexample, the use of lanyard type attachments, such as, for example,those used in Mantelmacher et al., U.S. Patent Application PublicationNo. 2007/0032883, attach and secure the liner at points well above itsdistal tip. Perspiration, which is emitted over the entire surface ofthe residual limb, tends to gravitate toward the distal tip of theliner, rather than at points higher in the liner. Thus, whileperspiration can cause sliding at any place on the liner/skin interface,sliding is prevalent at the distal tip. In order to surmount thedifficulties associated with sliding at the distal tip, lanyard systemsor similar methods have been developed which attempt to immobilize theliner through the application of radial and circumferential forces bystraps or lanyards at liner points above the distal tip. With lanyard orother methods which apply force at ulterior points of the liner, aresidual limb/liner can be effectively immobilized in a prostheticsocket. However, such systems can interfere with the comfort of wearingan elastomeric liner. Furthermore, in the absence of a means forevacuating perspiration from the liner, perspiration can accumulate tosuch a degree that much of the residual limb/liner interface is affectedby perspiration and sliding can occur, despite the presence of thesecuring means. In such a situation, the securing means can result inchafing or other skin breakdown which can interfere with the ability tocontinuously wear the liner for long periods of time. Means ofperspiration removal which have been used include vacuum ports ornipples to which a vacuum device is permanently or intermittentlyattached. Such ports are generally located near the distal tip. Theports can limit the ability of some patients to wear a liner for longperiods as the nipple can result in constant pressure through the lineron the residual limb at the site of the nipple, which wearers can findto be unbearable over time.

Another means of attaching a liner-covered residual limb to a prostheticdevice involves an attachment pin or spike which protrudes from thedistal tip of the liner and inserts into a hole in the prosthetic whichopens into the socket. The pin is usually supported by a disc or supportwhich is significantly harder and less elastomeric than the linermaterial. The support can be completely or partially embedded within thedistal tip of the liner. It is generally large, even to the point ofoccupying most of the distal tip. The support is generally large enoughto give adequate support to the pin, such that the need for other linersupport is minimized. The large support size also spreads the pressureexperienced by the distal tip during standing and ambulation over alarger area such that patient discomfort is minimized. The pin generallyhas ridges or grooves such that it can be releasably held by theprosthetic.

The connection of the elastomeric liner to the prosthetic socket by pinhas associated drawbacks, particularly if the pin is the sole means ofconnection. For instance, upon the distal accumulation of perspiration,the distal tip of the liner can be prone to pulling away from theresidual limb, causing sucking and pistoning which can be even worsethan that experienced with lanyard methods due to the immobilization ofthe distal tip of the liner by the pin attachment. In the absence ofother means of attachment, the stability of the limb can be compromised.

A prosthetic liner having the stability associated with a distal tippin, but without the same susceptibility to performance deteriorationdue to perspiration build up would represent a welcome advance in theart.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a liner in which avacuum is self-establishing upon ambulation. It is a further object ofthe present invention to provide a prosthetic liner having aperspiration voiding system which functions upon ambulation without avacuum pump. It is an object of the present invention to provide acomfortable prosthetic liner which securely locks into a prosthetic andbears an everted sweat port, yet permits ambulation without pain.

The present invention is a pin locking prosthetic liner apparatus havingreduced air breach and associated pistoning. The apparatus does notrequire the use of lanyards or securing means at points other than thespike in the distal tip region. The apparatus comprises a liner body, abuttress section, a sweat port comprising a one-way valve; at least onechannel through the liner body continuous with the sweat port, a pin,optionally integral with the sweat port, and, optionally, an innerfabric lining which does not come closer than a perpendicular distanceof 0.5 inches from the proximal edge of the liner. By “perpendiculardistance” it is meant the distance is measured along a projection of thevertical axis onto the liner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1—A cross-section of a first embodiment of the present inventioncomprising an elastomeric liner body (2), a fabric liner (3), an openchannel (5), a buttress (6), and a sweatport (4) adapted to contain aduckbill one way valve (not shown). Also shown is a fabric overliner(1).

FIG. 2—A cross section of a second embodiment of the present inventioncomprising an elastomeric liner body (2′), a fabric liner (3′), aclosable channel (6′), a buttress having an internally threadedconnection (7), a sweat port having external threads (4′), vent (8) anda one-way valve as more graphically illustrated in FIGS. 5A and 5B, anda pin (10). Also shown is a fabric overliner (1′).

FIG. 3—A cross-section of a third embodiment of the present inventioncomprising a buttress having two cylindrically symmetric sections (13),an elastomeric liner (2″) which has been melt sealed to the innerbuttress section, and a threaded channel (11). Note the elastomer of theliner has flowed through holes (12) in the inner buttress section. Alsoshown is a fabric overliner (1″).

FIG. 4—A perspective view of an integral sweat port and pin combinationcomprising a pin (14) and a sweat port (4″) having a vent (8′) extendingfrom the sweat port.

FIG. 5A—A top view of a separate sweat port (4′″) having vent (8″) andduck bill valve (9) with flaps 9A and 9B.

FIG. 5B—A side view of a separate sweat port (4′″) having vent (8″) andduck bill valve (9).

FIG. 6A—A perspective view of the sweat port (4″ or 4′″) and pin (14)combination having vent (15) extending axially through the pin.

FIG. 6B—A perspective view of the sweat port (4″ or 4′″) and pin (14′)combination having vent (16) extending radially from the pin.

DETAILED DESCRIPTION OF THE INVENTION

The present invention as illustrated in the figures comprises anelastomeric liner comprising an open proximal end having a proximal edgeand a closed distal end. The distal end comprises a distal tip. A sweatport (4, 4′, 4″ and 4′″) is positioned at the distal tip. The distal tipcomprises, within it or attached to it, a buttress (6, 7 and 13). Thebuttress generally comprises a polymeric material having a degree ofelasticity which is less than that of the liner (2, 2′ and 2″), or inother embodiments, the buttress comprises a support material, such asaluminum or other metals; or rigid plastics or other materials, whichare over laid with a polymeric material. In embodiments in which thebuttress contacts the prosthetic socket, the polymeric component of thebuttress softens the contact and prevents grinding which can wear thesocket and irritate the wearer. As illustrated in FIGS. 1 and 2, thebuttress can be embedded within the liner during liner manufacture, orin other embodiments, it is adhered to the end of the liner. Asillustrated in FIG. 3, it is preferably underlain by a section of theliner, regardless of whether it is embedded within the liner duringliner manufacture or it is adhered to the liner distal tip during orafter manufacture. The buttress generally has cylindrical symmetry aboutthe long axis of the liner. In one embodiment, illustrated in FIGS. 1and 2, it is a disc of a thickness less than liner thickness and isentirely embedded within the liner. In another embodiment, illustratedin FIG. 3, it is partially within the liner and partially outside theliner (“anchored” in the liner). This embodiment is particularly usefulin situations where a large buttress which is thicker than the liner isrequired. The buttresses (6, 7 or 13) each include a cylindricalextension having a bore therethrough for receiving a sweat port (4, 4′,4″ and 4′″).

In the embodiment illustrated in FIG. 3, the buttress is of a form suchthat a distal tip portion of the liner elastomer is between sections(13) of buttress having cylindrical symmetry. One of the buttresssections is embedded in the distal tip of the liner, and anotherbuttress section is externally attached to the elastomeric liner distaltip. Such an arrangement can be created by mechanically sealing aportion of the distal tip section between the two buttress components,or it can be achieved by casting the liner around the buttresscomponents, or otherwise including the buttress components in thefabrication and cooling of the liner, such that the buttress sectionsare essentially melt-sealed on both the inside and the outside of thedistal tip of the liner.

When the liner is in use, the buttress is structurally sandwichedbetween the residual limb stump and the socket, providing criticalsupport for the pin (discussed infra). In some embodiments, the supportis further improved in that the buttress is shaped to facilitateinsertion into the socket, or the socket has a shape which complementsthe shape of the buttress. In preferred embodiments, the buttressextends at least 0.5 cm from the vertical axis of the liner, and is atleast half the thickness of the liner body at its distal tip, andpreferably, at least as thick as the liner body at its distal tip.

The liner body which can be used in the system of the present inventioncomprises an elastomeric material preferably of a type compatible withlong periods of dynamic wearer contact. Such materials are known in artand may include the following polymer types and materials which includethem: polyurethanes; block copolymers such as styrene block copolymers,generally non-limiting examples of which may include SEBS, SEPS, SEEBSand SEEPS and other types of styrene block copolymers. Further examplesof styrene block copolymers which may be useful in the liner of thepresent invention include the so-called “controlled distribution”polymers, such as those disclosed in U.S. Pat. No. 7,226,484; UnitedStates Patent Application Publication Nos. 20070238835; 20050008669.Other potentially useful polymers may include so-called “crystalline”polymers, such as, for example, polymers disclosed in U.S. Pat. Nos.5,953,396; 6,420,475; and 6,148,830. The above list is non-limiting, andin general, the list of acceptable polymers and gels includes thoseknown in the art to be useful in the fabrication of prosthetic liners.By the term “gel,” it is meant a polymer having associated with it,through means known in the art, such as absorption, mixing or other, aplasticizer. A suitable liner which can be modified to include abuttress is the “EZ Gel” liner, available from Alps South L.L.C.

As illustrated in FIGS. 1-3, the liner body comprises a channel (5, 6′and 11) passing through the liner from its inner surface to its outersurface. The channel (6′) may be formed by piercing or punching, with orwithout the removal of elastomeric material from the liner. Asillustrated in the embodiment of FIG. 2, the liner is pierced such thatlittle or no material is displaced, and the channel (6′) is essentiallyclosed by the elastomeric response of the liner material. In such cases,the pressures associated with the ambulatory motion of the patient cancause perspiration produced during wear to be squeezed through thechannel. The channel (6′) essentially acts as a relief valve whichallows the elimination of perspiration emitted by the wearer. Theperspiration occupies a volume between the liner and the wearer,potentially giving rise to undesirable interruption of vacuum. In theforegoing embodiment, a closed channel can assist in maintaining andre-establishing the vacuum.

As illustrated in FIGS. 1 and 3, the channel (5 and 11) can also beopen. Such a situation is experienced with removal or displacement ofliner material, such as with a punch or heated awl-type tool. As thebuttress sections extend over the distal tip, the channel traverses themsuch that it opens out onto the distal tip i.e., the portions of thechannel traversing the elastomer and those traversing the buttresssections are continuous. It should be noted that the channels throughthe elastomer and those through the buttress sections need not be of thesame diameter. For example, it is permissible for the channel throughthe elastomer to be of the type described above in which perspirationcan be passed under pressure.

The distal tip of the liner, including the buttress, comprises a sweatport (4, 4′, 4″ and 4′″). The sweat port is continuous with the channel,and it is preferably located approximately at the distal apex. By“distal apex” it is meant the lowest point on the long axis of theliner, including the buttress, when its long axis is oriented verticallywith its distal tip pointing downward. As explained in greater detailinfra, the sweat port is attached to a pin (10, 14 and 14′) which isreceived by the socket of the prosthetic. In some embodiments, the pinmay not be precisely at the distal tip. For example, it may be desirablein some embodiments to attach the prosthetic in such a way that the pinis located at a point near, but not precisely at the distal apex.However, it should be noted that regardless of where the sweat port islocated, it is continuous with the channel through the liner. The sweatport is a nipple or port extending from or partially/fully embedded orrecessed in the distal tip of the liner. In a preferred embodiment, atleast a portion of the bore through the cylindrical extension of thebuttress is threaded, and the sweat port comprises matching threads bywhich it can be screwably attached to the extension.

The sweat port contains a one-way valve (9) which allows an exit forperspiration, air, and other liquids or gases which cause a volumeincrease between the liner and the wearer. The valve is small enough tofit within the sweat port and can be one of many different kinds ofcheck valves. In different embodiments, the valve is a duckbill, ball,diaphragm, swing, clapper, lift or other type of check valve. In apreferred embodiment, the one way valve is a duck bill valve.

The sweat port is attached to a pin which, in use, is inserted into aprosthetic limb. The pin is a spike of a durable material such asaluminum or other metal, which is generally in the range of from about1.5 to about 3 inches, which is inserted into a prosthetic limb. It canbear protrusions or other irregularities in profile which aid insecurely fitting the prosthetic to the liner. Optionally, the prostheticlimb can include a locking mechanism which maintains the prostheticsecurely in place.

The sweat port can be removably attached in series with the pin asillustrated in FIG. 2 to form a port/pin assembly. Such a connection canbe a threaded connection or other method of sealably engaging the portand the pin and generally includes a vent for the efflux of perspirationor another means of dissipating and draining the perspiration passingfrom the interior of the liner. In a preferred embodiment of the presentinvention, the sweat port is integral with the pin, depicted in FIG. 4,for example, where a vent is clearly visible on the side of theassembly.

In a preferred embodiment of the present invention, the liner body (2,2′ and 2″) has a fabric liner (3 and 3′) on its inner surface which overlays the distal tip, and in some embodiments extends along the innersurface a distance in the range of from about 1 to about 19 inches fromthe proximal edge of the liner. In some embodiments, the fabric linerextends to within no less than 0.5 inches from the proximal edge of theliner, and in other embodiments, to within no less than 1.0 inches fromthe proximal edge. A fabric which absorbs perspiration helps to wick ittoward the distal end of the liner. Preferred fabrics are those thatabsorb emitted perspiration, such as natural fibers, such as, forexample, felt, wool and cotton fabrics and materials, as well assynthetic fabrics and materials, such as, for example rayon, orlon andnylon. In other embodiments, a sock which has high perspirationabsorbency can function as the fabric liner, preferably extending to noless than 0.5 inches from the proximal edge. It is preferred that thefabric have a thickness in the range of from about 0.5 to about 3.0millimeters. It should be noted that regardless of fabric type andthickness, the present invention includes within its ambit embodimentscomprising fabrics or materials having the ability to wick and/or storeperspiration such that when weight is placed on the limb, the residuallimb compresses the perspiration bearing fabric or material, and some orall of the perspiration is forced through the channel and the sweatport.

Furthermore, the fabric liner can be an elastic fabric to facilitate itsability to stretch somewhat with the motion of the liner. In someembodiments, the fabric liner comprises fabrics which are manufacturedin such a way to optimize their elastic properties, especially when usedas a liner material for an elastomeric liner body.

A benefit of the present invention is that the constant elimination ofperspiration through the sweat port one-way valve aids in restoring avacuum to the liner/residual limb complex. A further benefit is that assmall amounts of sweat are constantly eliminated through the sweat port,they evaporate readily from the area surrounding the sweat port, andthus no need exists to dispose of larger amounts of perspiration.However, if desired, perspiration can be routed to a receptacle, such asa void in the prosthetic or another method of containment.

In general, even in the absence of fabric, the compression motion whichoccurs during ambulation acts to force accumulated perspiration throughthe channel into the sweat port, and ultimately through the one-wayvalve. In this way, emitted perspiration is voided before it can have asignificant effect on the vacuum, which is renewed with each step.

In general, liners of the present invention may comprise an elastic orelastomeric fabric which overlays all or a portion of the outer surfaceof the liner body. Such fabrics can have an elasticity which is greaterthan or less than the elasticity of the liner body. In some embodimentsof the present invention, the liner comprises elastic or elastomericfabrics to improve the fit of the liner and affect the overallelasticity of the liner.

It should be noted that the pin of the present invention can be usedwith both trans-femoral and trans-tibial amputees. It could be expectedthat in order to tailor the effectiveness of the inventive liner productand method to a particular circumstance, it may be expedient for one ofskill in the art to locate the sweat port/pin at a location other thanthe distal apex in order to facilitate an efficient evacuation ofperspiration. In general, because of the physical parameters involved inambulation, it is expected that the location of the sweat port would notbe more than an inch from the distal apex, and in all likelihood, asmaller distance. A liner having a sweat port which is relocated to meetthe perspiration drainage needs of a particular wearer does notrepresent a departure from the teachings herein and is encompassedwithin the scope of the present invention.

1. A liner comprising: a) an elastomeric liner body comprising an openproximal end and a closed distal end except for a centrally extendingchannel, said liner body defining an interior volume; b) at least onesymmetrical buttress element mounted centrally to said distal end ofsaid liner body and having a cylindrical member extending away from saiddistal end of said liner body; said cylindrical member defining a boretherethrough having an inlet end and an outlet end; c) said channel inthe distal end of the liner body having an inlet in fluid communicationwith said interior volume of said liner body and an outlet in fluidcommunication with said inlet end of said cylindrical member; d) a sweatport mounted in said outlet end of said bore of said cylindrical memberand defining a passageway therethrough in fluid communication with saidchannel, said sweat port having a one-way valve mounted in saidpassageway and adapted to provide one-way flow from said interiorvolume; e) a pin attached to said sweat port downstream of said one-wayvalve, said pin extending axially with respect to said liner body forsecurely fitting said liner to a prosthetic limb; and f) a ventextending through said pin and terminating in a vent port, said ventextending axially or radially through said pin to said vent port andfluidly communicating said passageway of said sweat port to thesurrounding environment.
 2. A liner as in claim 1, wherein said lineradditionally comprises a fabric liner or pad which does not extend tothe proximal edge of the liner body.
 3. A liner as in claim 2, whereinsaid fabric liner extends to no less than one inch from the proximaledge of the liner body.
 4. A liner as in claim 1, wherein a section ofsaid at least one buttress element is completely embedded within theliner body.
 5. A liner as in claim 1, wherein a section of said at leastone buttress element is attached to the exterior of said distal end ofsaid liner body.
 6. A liner as in claim 1, wherein said one-way valve isa duckbill valve.
 7. A liner as in claim 1, wherein said channel is aself-closable channel formed in said elastomeric liner body.
 8. A lineras in claim 1, wherein said sweat port and said pin are integral.
 9. Aliner as in claim 1, wherein the sweat port and pin are releasablyattached.
 10. A liner as in claim 1, wherein the sweat port and pin areattached via a threaded connection.